The aim is to make a detailed and careful investigation of tooth eruption and exfoliation with the view of gaining useful new information relative to dental health problems. Important aspects are to determine factors which regulate the exfoliation of deciduous teeth, the eruption of permanent successors and also factors which control the scheduling of eruption. The study involves experimentation on non-continuously erupting teeth in 15-23 week old beagles. Dogs were selected because they have non-continuously erupting teeth (a feature shared by man) that appear in two sets in contrast to the more frequently studied continuously erupting dental system of rodents. The basic experimental procedure will be to remove and/or replace the developing tooth, its follicle, the eruption pathway and surrounding bone and compare the effects of the induced change with controls during eruption and exfoliation. To reveal the teeth and their adnexa the overlying bone will be surgically removed via an intraoral approach. The experimental changes will be monitored by radiographic means during the several weeks following surgery and at selected times the experimentally altered tissues will be evaluated by histologic methods. Biochemical techniques to analyze collagen breakdown in the dental sacs and surrounding tissues of erupting premolars during various stages of eruption and exfoliation will be utilized to correlate biochemical and histologic data.